To be fair, historically the axe was an excellent weapon. It was easy to forge, and you could use the down-hook to pull shields and people off balance. Not a very defensive weapon though. Real life war axes were much smaller and faster than in fantasy pictures. Easier to hit with, but doing less damage.

A realistic stat would prob dmg5, atk2 def -1, len 1 and costing only 1 resource. Real axes probably used as much metal as a dagger and a dagger cost resource 1.

Not that you should implement these stats of course. Changing only weapon stats would unbalance every unit that uses these weapons.